Why I can't remove device tree node by /delete-node/ on overlay dts?

Question

I want to remove device node on overlay dts , but it doesn't work.
sample code as belows:

a.dtsi:
&soc {
    gpio_keys {
        compatible = "gpio-keys";
        label = "gpio-keys";
        pinctrl-names = "default", "sleep";
        pinctrl-0 = <&gpio_key_active>;
        pinctrl-1 = <&gpio_key_suspend>;

        vol_up {
            label = "volume_up";
            gpios = <&tlmm 85 GPIO_ACTIVE_LOW>;
            linux,input-type = <1>;
            linux,code = <115>;
            gpio-key,wakeup;
            debounce-interval = <15>;
            linux,can-disable;
            };
        };
}；

b.dts
#include "a.dtsi"
&soc {
    /delete-node/ gpio_keys;
};

I want to remove gpio_keys node on b.dts. But it doesn't work.
Any fellows can explain the reason ?

Answer 1

I have just achieved it using the exact syntax you did, based on what is stated here: Device Tree Source Undocumented

So by simply adding my own dts (as below), I was able to swipe out the unwanted nodes, and achieve the configuration I wanted.

#include "am335x-nand-eeprom-rtc.dtsi"
#include "am335x-pcm-953.dtsi"

//Remove ecap node
/delete-node/ &ecap0_pins;
/delete-node/ &ecap0;

// Remove touchscreen related nodes
/delete-node/ &i2c_ts;
/delete-node/ &ts_irq_pin;
/delete-node/ &backlight;
/delete-node/ &lcd_pins;
/delete-node/ &lcdc;
/delete-node/ &lcd_3v3;
/delete-node/ &panel;

&sound {
    status = "disabled";
};

Answer 2

according to the source below, it is not possible:

The /delete-node/ and /delete-prop/ directives are only used by the dtc compiler within a single compilation.

There is nothing in the format of a devicetree blob to represent the notion of deleting a property or a node.

You can not delete a property or a node in an overlay dtb.

https://lore.kernel.org/lkml/[email protected]/T/